Gemstone Potential Of Ethiopia - Geological Survey of Ethiopia

Transcription

Opportunities for Gem
resource development in
Ethiopia
Promotion Team,
Addis Ababa, 2009
Opportunities for gem resource development in Ethiopia
1 Introduction
A gemstone or gem, also called a
precious or semi-precious stone, is a
piece of attractive mineral which when
cut and polished is used to make jewelry.
Although not grouped as minerals, some
organic materials like amber, coral,
ivory, pearl etc.; are also used as
gemstone.
instrument called a refractometer is used
to measure the characteristic property of
the stone (refractive index). Emeralds,
rubies, sapphires and amethysts are all
doubly refracting (Figure 2), whereas,
spinels and garnets are singly refracting.
Opal, aquamarine, garnet, olivine,
tourmaline, topaz, sapphire, ruby,
amethyst, agate, jasper etc, are some of
the minerals used as gem. Their value
generally depends on four elements: the
beauty of the stone itself, play of internal
color its rarity, hardness and toughness,
and the skill with which it has been cut
and polished (Figure 1).
Figure 2. Varieties of amethyst purple-colored,
doubly refracting, with deep luster (Borena
Zone). Source: Geomuseum (GSE), GSE
(Photograph by Sentayehu Zewdie)
Figure1 Cut and polished jasper showing broad
areas of internal color ranging from light yellow,
brown to white (North Shewa). Source:
Geomuseum (GSE), GSE (Photograph by Sentayehu
Zewdie).
The beauty of gem can also be identified
by their optical properties. The most
important optical properties are the
degree of refraction and color. An
Other properties include fire, the display
of prismatic colors, dichroism, the
ability of some gemstones to present two
different colors when viewed in different
directions, and transparency. In certain
gemstones, notably opals, brilliant areas
of color can be seen within the stone;
and these areas change in hue and size as
the stone is moved (Figure 3).
Another physical test that can be given
to an unknown stone is the determination
of its specific gravity. For exact
determinations,
various
weighing
devices
are
used,
but
rough
approximations of the specific gravity of
lighter stones can be made by means of a
1
series of liquids of known specific
gravity. If the stone will float in a liquid
having a specific gravity of 4 and sink in
a liquid with a specific gravity of 3, the
specific gravity of the stone must lie
between these limits to be approximately
3.5.
The weight of a gem is always a factor
in determining price. Carat is the weight
measure for gemstones, with the
exception of pearls and coral. One carat
is equal to 200 milligrams or 0.2 grams.
Figure 4. Top grade precious opal with brilliant
green-red-yellow, blue internal fire (play of
colors). Menz Gishe District, Mezezo, Shewa,
http://www.ecvv.com/product/vp81030/Ethiopian
-opals.html
Figure 3. Mocha-colored precious opal with
brilliant green-red-blue internal fire (play of
colors) running throughout the opal (Menz Gishe
District,
Mezezo,
Shewa)
Source:
http://www.johnbetts-fineminerals.com/
Ruby, sapphire and emerald are highly
prized because of the intensity and
beauty of their colors. This phenomenon,
known as play of color, differs from fire
and is caused by interference and
reflection of the light by tiny
irregularities and cracks inside the stone.
Opals also exhibit milky or smoky
reflections. Gems that are fibrous in
structure show irregular
interior
reflections similar to those seen on
watered sample (Figure 4).
A special dark-field illuminator with a
binocular microscope is employed for
examining the interior of a gemstone to
determine whether it is of natural or
artificial origin, and to search for
inclusions characteristic of a given
gemstone. Clarity is the most important
characteristic in most gem. Flawless
transparency-freedom from inclusions
and cracks is critical to the beauty of
gems like diamond and topaz.
By their very nature gems are rare and
are not distributed throughout the crustal
rocks. Study indicates that there are over
3,000 different minerals, but only about
50 are commonly used as gemstone
(http://www.valuablestones.com/).
In Ethiopia gemstones occur in many
parts of the country. Amhara and
Oromia National Regional States are
well known by their potential resources
(Figure 5).
2
There are few mines in Ethiopia
(Table1) which basically depend on
artisanal mining system, and rather
which small-scale-miners dominated the
mining operation.
Almost all of
gemstone mining is done on a low-tech,
artisanal level-miners digging by hand or
with light equipment, seeking pay dirt
(Figure 6).
Figure 5. Aquamarine (Borena zone) crystal in
Borena Zone. (Oromia National Regional States)
Source: W/o Asselefech Mitiku, Ethiopian
Mineral Development Share Company.
Gemstone exploration has recent history
in Ethiopia. Quite a few studies were
conducted by foreign experts (Astrup,
1955; Kochemasov, 1971). Limited
explorations have been done by the
Ministry of Mines and Energy and
Geological Survey of Ethiopia (GSE)
(Solomon, 1977; Dubois, 1976). The
opal occurrences of central Shewa were
among the occurrences visited by Tucci,
2005. Recently (2007-2008) GSE and
(GDRBIRDMP, 2007) have conducted
exploration in Borena Zone, Oromiya
National Regional State (G/Selasse,
2009).
In most places, exploration is a hit-andmiss process, with deposits typically
being small and widely dispersed (Stone,
2002). Miners dig, and either they get if
lucky or they don’t.
Figure 6. Aquamarine mine in pegmatite. Jirme
(Borena Zone). Source: Tusguri, 2008.
Miners collect and sell rough gem to
local market. Currently, nearly all gems
in Ethiopia are exported as rough (Table
2). According to the Amharic journal,
“ETHIOPIA”, 1998 Eth.C, rough gem
991.95 kg was sold for $246,312.29 and
the finished one 2.5907555 kg sold for
$3,000.10.
A lot of information has been provided
for the world wide gem quality in web
site. On a recent eBay search, there are
different auctions offering Ethiopian
gem quality of opal. The world
gemstone and jewelry business indicates
that Ethiopian polished fire opal (North
Shewa, Menz Gishe), showing broad
areas of internal fire ranges of green,
yellow and red color with gray matrix,
has higher current price ($775) (Figure
7). The chocolate variety of rough opal
which shows the colorful snakeskin
pattern has the most striking and
distinctive behavior and deserves to be
3
called the queen of gemstones (Figure
8). Unit Price of Rough Gemstones for
Export are shown on Table 2.
Figure 7. Polished precious opal, showing broad
areas of internal fire ranging of green, yellow
and red with gray matrix in area (Menz Gishe
District, Mezezo, Shewa). Overall size mnL specimen
23×19×9mm Total weight=9.35Ct
Source: http://www.johnbetts-fineminerals.com/
Figure 8. Rough Ethiopian opal on international
market.Source:http://www.ecplaza.net/
http://yabsera.en.ecplaza.net/
Table 1 Current production and exploration of gemstone in Ethiopia
License
Name
Nationality License
Type
Mineral
Type
Romso
Minerals
P.L.C
Ethio-Swiss
Exploration Olivine(Peridot)
Romso
Minerals
P.L.C
Ethio-Swiss
Exploration Olivine(Peridot)
Region
Issue
Date
Remark
10/4/2005
Active
1/18/2007
Active
9/14/2006
Active
8/26/1998
Active
9/7/2004
Active
EthioCanadian
Exploration Opal
Romso,Dalecha
Oromia N.R.S
Aba Gume, Bule
funan, Gofa and
Buleshalewe,Dire
District, Borena
Zone
Diid Jarsa and
Oromia N.R.S
Fechena, Dire
District, Borena
zone
Romso, Dire
Oromia N.R.S
District, Borena
Zone
Feres Beret, Lay Amhara N.R.S
Meda, Zeno
Amba& Ayat Meda
locality, Mezezo,
North shewa Zone
Yigem and Molale Amhara N.R.S
Dutch
Exploration Opal
Awajo-Feres Beret Amhara N.R.S 12/24/2002 Active
Romso
Ethio-Swiss
Mining S.S Olivine(Peridot)
Minerals
P.L.C
Abay Natural Ethio-French Exploration Opal
Resources
Development
Plc.
AFAKA
MINERS
P.L.C
Kaleb
Instruments
Plc
Abay Natural
Resources
Development
Plc.
Locality
Ethio-French Mining S.S
Opal Nodule
Gorat, Yita &Kosta Amhara N.R.S 7/28/1999
Amba Locality, N.
Shewa Zone
Active
4
Table 2 Unit Price of Rough Gemstones or Export (per kg)
No.
Mineral Type
Minimum Price/kg
1
Amazonite
20.00 USD
2
Amazonite &Quartz
20.00 USD
3
Amber
1,186.40 USD
4
Amethyst
25.00 USD
5
Ammonite
25.00 USD
6
Apatite(Green/Blue)
50.00 USD
7
Aquamarine(Blue Beryl)
8,000.00 USD
8
Beryl
100.00 USD
9
Beryl(Emerald)
8,000.00 USD
10
Chalcedony
500.00 USD
11
Chrysoprase(Chalcedony)
100.00 USD
12
Ruby(Corundum)
8,000.00 USD
13
Citrine
300.00 USD
14
Sapphire(Corundum)
8,000.00 USD
15
Feldspar
100.00 USD
16
Garnet (Rhodolite)
300.00 USD
17
Hyalite(Opal)
50.00 USD
18
Iolite
400.00 USD
19
Jade
25.00 USD
20
Opal
350.00 USD
21
Opal(Rough)
350.00 USD
22
Orthoclase
10.00 USD
23
Peridot(Industrial)
20.00 USD
24
Peridot(Gem Olivine)
300.00 USD
25
Quartz
25.00 USD
26
Tourmaline
300.00 USD
5
2 Geology of Gemstone
The diverse geology of Ethiopia
comprises a variety of metallic, precious,
gemstone and industrial minerals. The
Precambrian metamorphic and igneous
rocks, especially the gneissic and
granitic terrain, in southern Ethiopia,
consist of potential resources of various
types of gemstone (GDRBIRDMP,
2007). Except garnet, which is
associated with high grade granitic
gneiss and schists, most of the gems are
hosted in pegmatite veins.
The Mega, Daya Dawa, Finnch-Wuha,
Corelli, Harshitme (Moyale) and Bonga
areas in southern Ethiopia are some
examples where gem quality garnet
occurs in granitic gneiss and schists
(Ethiopian Mineral Development Share
Company, 2005) (Table 3). Red garnet
associated with blue sapphire occurs in
pegmatite and quartz veins hosted in
granitic intrusion in areas of Cherri and
Arboro (GDRBIRDMP, 2007) (Table 3).
Garnet associated with tourmaline also
occurs in pegmatite veins in west of
Harakole village (Figure 9). The
pegmatite generally trend N20°W to
N40°W and are mainly composed of
quartz.
Figure 9.Garnet crystals at Harakole (Oromia
National Regional State Guji zone)
The ultramafic rocks are also known to
host gem minerals. Talc, serpentinite and
mica schists of Anno-Fulanto areas of
Southern Ethiopia, contain gem quality,
well crystallized, light to deep green
apatite (GDRBIRDMP, 2007) (Table 3).
Ultramafic xenolites of Megado
(Southern Ethiopia) are also known to
contain gems. The peridots are contained
within ultramafic xenoliths hosted by
vesicular basalt (GDRBIRDMP, 2007),
and they some times forms nodules of
circular to lensoidal shape containing
numerous grains (Figure 9).
Figure 10. Peridot Contained in Mantle Nodules
at Megado (Borena zone) source: GSE
Geomuseum (GSE)
(Photograph by Sentayehu Zewdie)
There are several gem bearing
pegmatites hosted in the Precambrian
gneiss and granitic rocks. Some
pegmatites
are
associated
with
ultramafic rocks. The pegmatites are
composed mainly of quartz, feldspar and
books of muscovite. In the Aflata
Formation, in Baya-Coorrelli (Baya
Gundi) these pegmatites occur within
amphibole and biotite gneiss and
ultramafic rocks. Here the pegmatite
hosts a variety of gem minerals like
garnet, tourmaline, aquamarine, and
corundum with a possible potential to
6
host emerald. Aquamarine is the most
frequently
occurring
mineral
in
associated with quartz and feldspar
(Figure 11). Small grains of red garnet
are found within the quartz. The
Aquamarine is well crystallized,
hexagonal in shape; and transparent with
light blue color (GDRBIRDMP, 2007).
Much of the central part of the country is
underlain by Tertiary and younger
volcanic rocks, mainly basalt. These
rocks are part of the Eastern escarpment
of the Ethiopian plateau on the margin of
the main Ethiopian Rift System. It
consists of five horizons of flood basalt
interlayered with
paleosoils and
agglomeratic tuff, pyroclastic material
and unconsolidated tuffacious horizons.
The opal is located within OligoceneMiocene-age Trap series of flood basalt
sequence with rhyolitic volcanic
interbeds. The opal bearing rocks are
found within the Ambalege Formation
which consists of “transitional and
subalklaline basalts with minor rhyolites
and trachite eruptions”. The opal comes
from light grey, welded and glassy
volcanic tuffs those crops out along the
north face of Yita Ridge, Mezezo, North
Shewa. The opals occur as nodules
within a 9 to 15 feet thick zone along the
base of the tuff (Figure 12).
Figure 11. Aquamarine 3cm long and 1cm
diameter light blue, and transparent, partially
embedded in quartz matrix of pegmatite (Jermi,
Borena Zone). Source: Tusguri, 2008
In Web Degero area, the gem-bearing
(aquamarine and emerald) pegmatites
are medium grained with dark lenses of
mica, quartz veins of variable size and
lesser amount of feldspar. In Darmi
Dama, Kilkile and Kenticha (Southern
Ethiopia), the gems (beryl) are
associated with rare metal. The beryl is
bluish green, fractured and semitranslucent on the surface.
Figure 12.Opal-bearing tuff containing nodule of
opal (Yita Ridge, Mezezo, North Shewa). Source
Geo-Geomuseum (GSE) (GSE) (Photoraph by
Sentayehu Zewdie).
7
The main zone is about a mile long with
sporadic exposure along the ridge. The
opal bearing tuff is generally horizontal
bed that appears to be quite extensive. It
is overlain by cap rock of columnar
basalt that protected the tuff from
erosion. The nodules’ diameter ranges
below one to above 8 inches with an
average of 4 inches. Small nodules tend
to be spherical, but the larger ones are
oval shaped (Figure 13).
Figure 13. Different sizes of nodules of opal
(North Shewa): W/o Asselefech Mitiku, Ethiopian
Mineral Development Share Company.
(Photograph by Sentayehu Zewdie).
Table 3. Summary of the Gemstone
Belts of the Genale-Dawa Basin
(GDRBIRDMP, 2007)
Megado
AnnoFulanto
CherriChebi
Arboro
BayaCorrelli
Web-Degogo
BitataHarakole
Mineral
peridot
Apatite
Garnet,
Sapphire
Aquamarine
garnet
tourmaline
Aquamarine
Garnet,
tourmaline
Host Rock
Basalt
Serpentinite
Quartz,
pegmatite
pegmatite
pegmatite
pegmatite
Country
Rock
Basalt
Serpentinite
Granite,
gneiss
Ultrabasic,
gneiss
Ultrabasic
Granite
Lateral
extension
Extensive
>8km
Discontin
uous
>10km
>15km
>10km
Occurrence
Colony
Individual
Discrete
Discrete/
individual
Colony
N-S
N-S
Discrete,
colony
(group)
E-W
N-S
N20˚WN40˚W
Quartz,
feldspar
Borena
Quartz,
feldspar
Borena
Quartz,
feldspar, mica
Borena
Quartz,
feldspar
Guji
Trend
----
By product
Olivine
Talc
Zone
Borena
Borena
8
3 Gemstone Occurrence
3.1 Opal Occurrence
Opal is a mineraloid gel which deposited
at a relatively low temperature and may
occur in the fissures of almost any kind
of rock, being most commonly found
with limonite, sandstone, rhyolite, and
basalt
(Mineral Development Share
Company,
2005).
The
special
characteristic of opal is their play-ofcolor, a display of rainbow-like hues
which change with the angle of
observation. Opal is sensitive to heat,
pressure and knocks and being affected
by acid and alkaline.
Opal has been a popular gem for many
centuries possessing a very interesting
structure (Figure 14).
150 to 300 nm in diameter in a
hexagonal or cubic closed-packed
lattice. These ordered silica spheres
produce the internal colors by causing
the interference and diffraction of light
passing through the microstructure of
opal.
The chemistry of opal is primarily SiO2
and varying amounts of water. The
amount of water varies from 5 -10% and
greater. Nonetheless random chains of
silicon and oxygen are packed into
extraordinarily tiny spheres. These
spheres in most opals are irregular in
size and inconsistent in concentration.
Yet in precious opal, the variety used
most often in jewelry, there are many
organized pockets of the spheres. These
pockets
contain
spheres
of
approximately equal size and have a
regular concentration, or structure, of the
spheres. This has the effect of diffracting
light at various wavelengths, creating
colors. Each pocket produces a different
color, with a different intensity
depending on the angle from which a
viewer sees it. The multicolored flash of
light emission gives a truly beautiful and
valuable look (Figure 15).
Figure 14 Oval cabochon of white precious opal
with brilliant green-orange internal fire, from
Menz Gishe District, Mezezo. Source:
http://www.johnbetts-fineminerals.com/
Precious opal shows a variable interplay
of internal colors due to its internal
structure. At the micro scale precious
opal is composed of silica spheres some
Figure 15. Multi colored, beautiful precious
opal with brilliant green-orange internal fire,:
Source:http://www.ecvv.com/product/vp81030/Et
hiopian-opals.html
9
The name opal probably is derived from
the Indian Sanskrit name for precious
stone; upala. It has been mined for
centuries, at least since Roman times, in
several areas of Czech Republic.
The opals have generally large size, and
wide range of base colors, including
clear, translucent,
white, yellow,
orange, red, blue, green and dark reddish
brown (Figure 17 ).
Today most precious opal comes from
Australia with significant sources from
Mexico and the Western United States
(http://en.wikipedia.org/wiki).
In Ethiopia precious opal is found in
Tertiary volcanics within rhyolitic
ignimbrite or tuff as concretions that are
covered by compacted acidic ash shell
with different colored amorphous silica
in center (Figure 12 and 16 ).
Figure 17. Cut and polished opal show in an
incredible array of colors (North Shewa).
Source: Geomuseum (GSE). (Photoraph by
Sentayehu Zewdie).
The Imbitata, Gift Bahir, Gorat and
Koste Amba opal is found within
Tertiary volcanics, in welded lapilli, and
rhyolitic ignimbrite as nodules (Figure
18).
Figure 16. Nodules of opal within rhyolitic
ignimbrite covered by acidic ash. (Yita Ridge,
Mezezo, North Shewa) Source`-Geomuseum
(GSE) (Photoraph by Sentayehu Zewdie).
Opal is reported to occur in central
Ethiopia, in Amhara Regional Sate,
Northern Shoa, around Menze and Gishe
and Bulga zone, Mezezo and Sela
Dingay wereda at: Yita, Koste Amba,
Gift Bahir, Gift Gaymeda, Lay Beret,
Wenze Midir, Gorat and Wedera
Kebeles. These localities (Kebeles) are
about 225 km NNE of Addis Ababa and
5 to 6km NNW of Mezezo at the flank
of
Debrebrehan-Mehalmeda
road
(Figure 51).
Figure 18. Large size opal, dark brown base
color with flashes of red, green and blue fire
(Yita Ridge, Mezezo, North Shewa). Source:
Tucci, 2005; http//www.rockngem
The nodules are varying in diameter
from 1 to 6cm. The color varies from
red (fire) to light grey, and dominantly
glassy (Figure 19). There occur nodules
10
which contain both none precious and
precious opal. Some nodules are
fractured. However, the naturally
occurring fractures are not big problem
for processing (Tucci, 2005; http//
www.rockngem).
In Imbitata the opal bearing outcrop
extends for about 32m with a depth of
2m. According to Amharic Journal of
“Ethiopia”, 1995 Eth.C., the opal reserve
of North Shewa, including Imbitata were
calculated to be 2.83 million kg.
A
B
Figure 20. A) Rough solid. multicolored, 2.7CT
desert
crystal
opal
(Wello).
Source:
(http://cgi.ebay.com/) B) Bright fire, 3 CT opal
in 14k pendant 14k yellow gold. Price 139$.
(Wello, Ethiopia). (http//www.esagefinejewlary).
Figure 21 Multicolored, fire opal 6.2 CT
(Gonder) Source: (http://cgi.ebay.com/)
Figure 19. Light grey glassy nodules and
polished variety of opal (Imbitata, North Shoa).
Source: W/o Asselefech Mitiku, Ethiopian
Mineral Development Share Company. .
There are also newly discovered opals in
Wello and Gonder in Wadla Dilanta and
Tikil Dingay respectively. The opals are
multicolored (brilliant), rough with
varying size. Nugget type brilliant,
rough opal of Wello is called “Desert
Crystal opal” (http://cgi.ebay.com/)
(Figure 20-21).
11
On a recent eBuy market on the internet,
there are different auction offering for
the Ethiopian opal (Figure 22 ).
15mm x 11mm and a gigantic 8mm
thick. This gorgeous gem weighs
approximately 8 carats. Including the
fancy floral engraved bail, the pendant
measures a total of 25mm long, about 1
inch long.
A
A
B
B
Figure 22 A) Cut and polished, brown, red, blue
and green , 3.6 CT opal. Price $39 (Ethiopia).
(http//www.esagefinejewlary). B) Golden yellow
1.17 CT opal$ 9.99 (Ethiopia).
Pieces of opal is some time completely
crafted in solid gold and gives beautiful
color, which flashes in different shades
of color. Such type of opal is sold about
695 US Dollar (Figure23-24).
Figure 24 A) 2.3 CT red, blue and green opal
$399 (Ethiopia). B) Bright fire, 8.3 CT opal
139$. (http//www.esagefinejewlary).
Pieces of nodules with varying size and
color are capable of being cut and
polished and show incredible array of
colors and shape (Figure 25). Rough and
unprocessed opal-bearing nodule is
different from cut and polished opal in
prices (Figure 26-27).
Figure 25. Rough opal different color flashes in
shades of neon red, yellow and green.
(Ethiopia). http://yabsera.en.ecplaza.net/
Figure 23. Opal crafted in solid 14k yellow gold
color flashes in shades of neon red, yellow and
green (15X 11X 8mm).( www.esagefinejewlery).
The back of this opal is just as colorful
as the front. It measures approximately
12
Figure 26 eBuy market showing current price
13
Figure 27 eBuy market showing current price of
Ethiopian
opal
http://www.panjshergems.com/ethiopian-opal.html
14
3.1.1
Opportunity
There is an opportunity for investors to
conduct systematic prospecting and
exploration in the local mining areas of
Yita Ridge and surrounding areas
following the opal bearing ignimbrite.
Small scale miners have traditionally
mined opal since it was discovered in
1994 (Tucci, 2005). The mining is done
manually by local people, using simple
hand tools, digging pits into the cliffs
along the face of the outcrop (Figure 28).
Extensive tunneling into the opal bearing
rock has not occurred. This indicates that
there is an opportunity of
large scale
mining using mechanized mining
equipment.
Figure 28. Digging pits into the cliffs along the
face of ignimbrite outcrop (Yita Ridge, Mezezo,
North
Shewa).Source:
Tucci,
2005;
http//www.rockngem
According to current e-Buy market on
the internet the Ethiopian opal has a
good international market; and there is a
possibility of potential investors to
involve in the sector (Figure 29).
Figure29 Different prices of Ethiopian opal on eBay market
15
There are two small gem processing
industries; one in Addis Ababa and the
other in Bahir Dar of Amhara National
Regional State. For opal-mining industry
to be successful in Ethiopia, it is
essential that those opals have to be cut
and
polished for finished jewelry.
of the seeds of a ripe pomegranate
(Figure 30).
Currently, the Ministry of Mines and
Energy is encouraging the private sector
to take the lead in developing modern
gemstone mining and establishment of
jewellery manufacturing industry.
3.2 Garnet Occurrence
Garnet is a rainbow of gemstones. With
the exception of the blue, it is found in
every color of spectrum. It may have the
red of fine ruby or the green of rich
emerald. Its good hardness of 7 to 7.5 on
the Mohs scale makes the garnet
different from other gemstone. With a
few minor exceptions, it applies to all
the members of the garnet group, and it
is the reason for the excellent wearing
qualities of these gemstones. Garnets are
relatively insensitive and uncomplicated
to work with. The only thing they really
don't like is being knocked about or
subjected to improper heat treatment. A
further plus is their high refractive index,
the cause of the garnet's great brilliance.
The shape of the raw crystals is also
interesting. Garnet means something like
'the grainy one', coming from the Latin
'granum', for grain. This makes reference
not only to the typical roundish shape of
the crystals, but also to the color of the
red garnet, which often puts one in mind
Figure 30. Grain like garnet crystals mostly
almandine from Harekelo, Borena zone: W/o
Asselefech
Mitiku,
Ethiopian
MineralDevelopment Share Company
The main representative of garnet are
pyrope (red), almandine (red with violet
tint), rhodolite (purplish red or rose) and
spessartite (orange to red-brown).
Deposits can be found in Burma, China,
Madagascar, Siri-Lanka, South Africa,
Tanzania,
the United States of
America, Brazil, Czech Republic,
Austria and India.
In Ethiopia gem quality garnet are
known to occur in southern Ethiopia
hosted in pegmatites within the PreCambrian
gneiss
and
schists,
Explorations indicate that there occurs
gem-bearing pegmatite at about 10 and
30km east and west of Harkakole village
in Oromiya National Regional State.
Here garnet with subordinate tourmaline
is found within the quartz portion of the
pegmatite and makes up to 30% by
volume. The color of garnet varies from
orange to deep red and is well
crystallized with rhombohedral shape
reaching up to 5cm in diameter
16
(GDRBIRDMP, 2007) (Figure 31) . The
pegmatite trends north-east for about
10km.
Figure 31. Well, crystallized gem-quality garnet
(Harakole,
Borena
zone).
Source:
GDRBIRDMP, 2007
Figure 32 well developed garnet crystal
(Almandine) 10cm in diameter (Udet, Sidamo)
Source: Geomuseum (GSE). (Photograph by
Sentayehu Zewdie).
Similar garnet bearing pegmatite also
occur at Hararafama and Gidole, 10 and
30km
from
Harkakole
village
respectively (Figure 51)
Local mines of garnet were reported in
Mega, some 140km from Mega town
and Daya Dawa about 100 to 120km
from Hagere Mariam town. The garnet
crystals are reddish brown, coarse
grained, 1-3cm in diameter and
transparent to translucent (Unpublished
report, EMDSC, 2005).
There are also local mines in FinchWoha, Baya, Corelle, Harshitme (20km
east of Moyale and Bonga area. Red
garnets(Almadine) up to 4cm long are
reported. The garnet crystal found in
Udet, Sidamo ranges up to 10cm size
(Figure 32)
The Buri Ejersa garnet, which is located
1km south of Dawa, are isometric, up to
1cm in diameter, translucent and some
shows intergrowth of crystals (Tusguri,
2008) (Figure 33 )
Figure 33 Inter growth of garnet (pyropealmandine) crystals embedded in gneiss (Buri
Ejersa locality) Source: Tesfa, 2008.
3.2.1 Opportunities
There are several occurrences of gemvariety garnet in southern parts of
Ethiopia.
Except
Harakole,
no
exploration activities have been done.
Therefor there is an opportunity for
investors
to
conduct
systematic
prospecting and exploration in both
explored and local mining areas.
17
3.3 Peridot Occurrence
Peridot is the best known gem variety of
olivine, a species name for a series of
magnesium-iron rich silicate, forsteritefayalite series mineral. It is one of the
"idiochromatic" gems, meaning its color
comes from the basic chemical
composition of the mineral itself, not
from minor impurities, and therefore it
will only be found in shades of green.
This bright yellow-green to green
gemstone has caught the fancy of
humans for thousands of years.
In the gemstone trade it is called
'peridot', derived from the Greek word
'peridona', which means something like
'to give richness'.
The peridot is one of the few gemstones
which come in one color only. The rich,
green color with the slight tinge of gold
is caused by very fine traces of iron. The
intensity of the color depends on the
amount of iron actually present. The
color itself can vary over all shades of
yellowish green olive, and even to a
brownish green (Figure 34). Peridot is
not particularly hard - only 6.5 to 7 on
the Mohs scale - but it is easy to look
after and fairly robust. Peridot cat's eyes
and star peridot are particularly rare and
precious. It has vitreous and greasy
luster, and is not resistant to acids. It
tends to burst under great stress;
therefore it is sometimes metal foiled.
Figure 34 Green to yellowish green peridot
hosted within olivine basalt (Mega area, Borena
Zone); Source: Tsegaye Girma, Ethiopian
Mineral
Development
Share
Company.
The peridot is cut in accordance with its
crystal shape, mostly faceted or in
classical table cuts, or round, antique, as
an octahedron or oval (Figure 35).
Figure 35. Cut and polished, rounded shape
peridot (Mega area, Borena zone).Source: W/o
Asselefech
Mitiku,
Ethiopian
Mineral
Development Share Company. . (Photograph by
Sentayehu Zewdie).
18
Smaller crystals are cut into standardized
series stones, larger ones into
imaginative one-offs. Cabochons are
made if the material contains more
inclusions, for the domed cut brings out
the fine silky shine of the inclusions to
their best.
Deposits have been found in Australia,
Brazil, China, Kenya, Mexico, Palestine,
Siri-Lanka, South-Africa, Tanzania,
Norway and Arizona (Schumann, 2001).
In Ethiopia peridot deposits are reported
to occur in south Oromiya National
Regional State, 665 km south of Addis
Ababa, around Mega, at the localities
Dillo,
Gorain,
Megado,
Albora,
Bulegendo, Gofa Gedo, Tassy and
Chew-Bet
(Figure 51). The area is
found within a north-south aligned
caldera that is apparently confined into
N-S trending faults (Ethiopian Mineral
Development Share Company, 2005).
The rock containing the gem is olivine
basalt, found as intercalation within
agglomerate tuff, at different depth of
caldera especially near-vent agglomerate
tuffs. The basalt layer reaches up to
1.5m thick and composed of grey to
black olivine amygdules, gneiss and 1520cm bombs of fine grained olivine
(Figure 36. Crushed bombs yield olivine/
peridot up to 2x2 and 3x3 mm. First
grade peridot occurs in near-vent
agglomerate.
In Albora and Bulegendo there occur
crystals of gem-variety olivine/peridot,
other than the common fine grained
yellowish-green
cloudy
variety
(EMDSC, 2005). The quality of the
Bulegendo peridot is categorized under
highest class possessing bright green,
yellowish green and olive green color
with sizes larger that 10x10x10mm. The
occurrence is a fissure type, 15km long
volcanic edifice, traced N-S along the
western slope. The overall surface of the
deposit is slightly in excess of 1km2.
Figure 36 Yellowish green olivine bomb
containing peridots (Mega, Borena Zone):
Source Geo-Geomuseum (GSE), GSE.
.
The olivine crystals and bombs were
crushed, measured, weighted and the
area was delineated. A thickness of one
meter layer from prospecting pit was
taken to calculate the reserve. The
reserve was calculated for a depth of 1m
and area of 9km2. Average thickness of
lava flow is assumed to be 6-8m.
Inferred reserves (Category P2) of the
Bulegendo deposit were estimated at
615.6 kg of highest grade, 1,440 kg first
and second grade (total 2,055.6 kg).
19
3.3.1 Opportunities
The Mega area is well known by its
olivine/peridot occurrence. The data
obtained so far indicates that the area,
especially the Albora and Bulegendo are
promising
to
conduct
further
exploration.
3.4 Beryl occurrence
The mineral beryl is a principal store of
beryllium in the earth's crust. In its rare
gem form it is notable for a variety of
vivid allochromatic colors, each of
which has different gem names. All are
nearly chemically identical but contain
trace elements of Cr, Fe, Mn and Al to
give respective color of green beryl
(emerald), blue (aquamarine) and pink
(Morganite). These element substitute Al
in the crystal lattice and act as
chromophores.
Indeed, because of a
relatively low refractive index and low
dispersion, color is the prime factor that
accounts for the popularity of most gem
beryl (Figure 37).
limestone. The volatile fraction of the
vein liquid or magma provides Be and
the host rock requisite Al.
In Ethiopia gem quality beryl is found in
Precambrian gneiss and schists hosted in
pegmatite. In southern Ethiopia, in
Oromiya National State, the gem mineral
occurs in pegmatites within amphibole
and biotitie gneiss of the Aflata
Formation. Big crystals of beryl up to 8
to 17cm in width and 22 cm in length
were identified in Baya Gundi area in
Borena Zone, Oromiya National
Regional State (G/Selasse, 2009)
(Figure 38).
Figure 38. Beryl (Aquamarine crystal)
17cmx22cm size from Baya Gundi. Source:
Geomuseum (GSE) (Photoraph by Sentayehu
Zewdie).
The aquamarine is light blue, semi
transparent to semi translucent, well
crystallized and hexagonal in shape and
is embedded in the quartz matrix of the
pegmatite (Figure 39).
Figure 37. Light blue translucent beryle,.
Aquamarine crystals (Borena Zone, Jirme
locality. Source: Tusguri, 2008).
Gem beryl is found nearly exclusively in
hydrothermal veins, pegmatites, or at the
contacts of larger igneous intrusions that
invade aluminous schist, shale or impure
20
The gem minerals found in Degogo area
(Borena Zone) are mainly aquamarine
and emerald hosted in pegmatite
(GDRBIRDMP, 2007). In Degero
Licence area, owned by Web Degero
Gemstone Plc; the aquamarine crystals
are hosted in quartz vein. The gem is
well crystallized, blue in color,
hexagonal and transparent with no
visible fracture plane.
Figure 39. Light blue, transparent aquamarine
partially embedded in quartz matrix (Baya
Gundi) Source: Berehe G/Selase.
Similar prismatic crystals of aquamarine
semi transparent to semi translucent,
well crystallized hexagonal, up to
3cmx3cm were reported from a 1m
In Dido Jarso, 11km south of Mega,
beryl crystals occur associated with
garnet, vermiculite, muscovite and black
tourmaline
(EMDSC,
2005).
Aquamarine in Chembi, Kilkile and
Kenticha area, Borena Zone, are known
to occur associated with rare metal class
pegmatite (EMDSC, 2005) (Figure 41).
Figure 41 Rough and polished aquamarine from
Borena Zone Source: W/o Asselefech Mitiku,
Ethiopian
Mineral
Development
Share
Company. (Photoraph by Sentayehu Zewdie)
depth exploration pit of Jermi locality,
8km N of Derme town (Figure 40).
Figure 40. Prismatic, light blue, and transparent
aquamarine embedded in quartz matrix of
pegmatite (Jermi, Borena zone).
Source:
Tusguri, 2005.
Among the beryl gem, emerald is only
reported in three areas of Oromiya
National Regional State, around Mega,
near the localities of Das, Dillo and Web
(Figure 51). The emerald crystals are
hosted in pegmatite along the contact
with granitic gneiss and ultramafic rocks
(Figure 42). Trenches were dug by local
miners along this contact to collect
emerald crystals.
21
Figure 43. Finished and rough scapolite (North
Shewa). Source: W/o Asselefech Mitiku,
Ethiopian
Mineral
Development
Share
Company.. (Photograph by Sentayehu Zewdie).
Figure 36. Emerald (green) and aquamarine
from Borena Zone. Source: W/o Asselefech
Mitiku, Ethiopian Mineral Development Share
Company.
3.4.1 Opportunities
Jasper and chalcedony occur in North
Shewa (Mehal Meda), Kutaber Wello,
Debresina (Shewa), Jima and Mega. An
indication of good quality jasper is
reported 2-3 km far from Mehal Meda at
the locality called Gedenbo (Figure 44).
White apple green chalcedony and jasper
are reported in NE of Mega, 3km south
of Das village (EMDSC, 2005).
Exploration in Baya-Gundi and Jermi
areas of Borena Zone indicates that there
are possible potential of aquamarine for
future development.
3.5 Other gemstones
Other gemstones known in Ethiopia
include: sapphire, jasper, chalcedony,
precious quartz, tourmaline, ruby,
amazonite, amethyst, obsidian, scapolite
agate, petrified wood, etc; (Figure 43
and Table 4).
Figure 44. Different colored finished jasper from
North Shoa. Source: W/o Asselefech Mitiku,
Ethiopian
Mineral
Development
Share
Company. (Photoraph by Sentayehu Zewdie)
Precious quartz occurs in many parts of
the country, these include: amethyst,
clear purple or violet variety, and color
less quartz crystals (Figure 45). Some of
these occurrences are reported in Tigray,
Borena Zone, Oromiya National
Regional State and Jigiga (Somaili
22
National Regional State). (EMDSC,
2005).
A)
veins in gneissic and ganitic terrain
(Figure 47).
B)
Figure 45. Rough and finished, precious quartz
varieties, A) colorless quartz B) clear purple
amethyst (Borena zone). Source: W/o Asselefech
Company. . (Photograph by Sentayehu Zewdie).
Obsidian is commonly found in the rift
valley, particularly on the top of
volcanic domes and craters. Except the
rare colors of brown, grey, blue and
green, obsidian has shiny black color
(Figure 46).
Figure 47. Rough and finished amazonite
(Kenticha, Guji Zone). Source: W/o Asselefech
Company. (Photograph by Sentayehu Zewdie)
Tourmaline is one of the commonly
found mineral found associated with
garnet
in
pegmatites.
varieties and species,
Among
the
black tourmaline
(schorl) are reported to occur in Bisu
Duga and Baya-correli (Borena Zone)
and Gidole, Bitata-Harakole (Guji Zone
Table 4, Figure 48 and Figure 51). Green
tourmaline are also seen in hands of
local people in Borena Zone and yet the
exact locations are not identified.
Figure 46. Black, shiny, polished obsidian
(Lanngano) Source: W/o Asselefech Mitiku,
Ethiopian
Mineral
Development
Share
Company. (Photograph by Sentayehu Zewdie).
Amazonite occur in pegmatites of Chebi,
Guji Zone, Oromiya National Regional
State and Konso wereda in SNNPRS
(Figure). It is found hosted in pegmatitic
Spaphire associated with garnet also
reported in Guji and Borena Zone in the
localities called Chebi, Bitata Harakole,
Gidole (Guji Zone), Lai, Coreeli, Cherichebi Arbboro (Borena Zone, Table 4
Figure 51) .
23
Gem quality, well crystallized, light to
deep green apatite are also reported
(GDRBIRDMP, 2007).
Figure 48. Black tourmaline crystal (Borena
Zone). Source:
GSE Geomuseum (GSE)
(Photoraph by Sentayehu Zewdie).
Petrified wood occur in many parts of
Figure 50. Gem variety of agate (North Shewa)
Source: Geomuseum (GSE) (Photograph by
Sentayehu Zewdie).
North Shoa, in the localities Kimir
Dingay, Mehal Meda, Ankober, Sela
Dingay, Jehur, Lemi, Gift Mariyam and
Yita Micheal areas. In Chebi–Arboro
(Borena Zone), similar petrified wood is
repported as pseudomorphus of agate
(Table 4 and Figure 49, 50 and 51).
Figure 49. Petrified wood (Borena Zone).
Source: Geomuseum (GSE) (Photoraph by
Sentayehu Zewdie).
24
Table 4 Gemstone occurrences in Ethiopia
Gemstone
Host Rock
1
Aqua marine
pegmatite
2
Peridot (Olivine)
3
Garnet, Sapphire
4
Tourmaline
5
6
7
Apatite
Petrified Wood
Opal
8
Amazonite
Localities
No.
Regional
state
(Borena ONRS, SNRS
Webdegogo,
Baya-correli
zone)Dermidama,
Kenticha (Guji zone), Bombas
serpentinite
Dilo, Megado, Gorai, Didi- Jerso caldera, ONRS
Bulegendo, Alabora, (Borena Zone)
Pegmatites and quartz
Lai, Coreeli, Cheri-chebi Arbboro (Borena ONRS
Zone), Bitata Harakole,Gidole(Guji Zone),
Pegmatites
Baya- correli, Bisuduga(Borena Zone), Gidole, ONRS
Bitata- Harakole (Guji Zone)
Ultramaffic rocks
Anno-fulanota (Guji Zone)
ONRS
Basaltic rocks
Chebi–Arboro,(Borena Zone)
ONRS, ANRS
Sedimentary and volcanic Gorat, Yita and Kosta-Amba,Molale, Mezazo, ANRS
environment
Laymeda, Zeno Amba and Ayat- meda , North
Shewa Zone
Pegmatite
Chembi (Guji Zone), Konso Sp.Wereda
ONRS,
SNNPRS
9
Agate, Jasper Amethyst Sedimentary and volcanic In Many parts of Ethiopia
environment
ANRS = Amhara National Regional State
ONRS=Oromiya National Regional State
SNNPRS= Southern Nations, Nationalities and Peoples Regional State
25
Figure 51 Location map of gemstone occurrence in Ethiopia
26
Table 5. Geographic coordinates of gemstone occurrences shown on the location map
Mineral
Easting
Northing
Locality
Mineral
Easting
Northing
Locality
Beryl
441327
592100
unknown
Beryl
496267
600841
Jermi
Garnet
441070
592174
unknown
Garnet/ Sapphire
389875
563264
cheri
Garnet
440872
592240
unknown
Petrified
390110
999690
Chebi Arboro
Garnet
439966
594351
unknown
Tourmaline
441170
591933
Bisu Dega
Garnet
439834
594426
unknown
Tourmaline
441745
590650
Bisu Dega
Beryl
439792
594865
unknown
Beryl
438597
603327
unknown
Garnet
439441
594990
unknown
Garnet
438846
602626
unknown
Beryl
439181
595003
unknown
Garnet
476831
588235
unknown
Garnet
440429
601226
unknown
Opal
568515.6
1096417
Unknown
Garnet
440002
601265
unknown
Opal?
573054.2
1110953
Unknown
Garnet
439397
601695
unknown
Garnet
475999.3
604253.6
FinchWoha
Garnet
440148
601707
unknown
Garnet
439056.1
584010.6
Baya
Garnet
439090
601867
unknown
Garnet
453823.4
572944.9
Corelli
Red garnet
439916
601889
unknown
olivine
355665.3
470834.8
Dillo
Garnet
Beryl/
Garnet
439180
601905
unknown
olivine
406647.1
430076.4
Mega/megado
439191
602179
unknown
olivine
416732.5
430066.9
Gofa Gedo
Garnet?
439498
602208
unknown
olivine
411178.4
427431.2
Tassy
Beryl
439238
602234
unknown
olivine
440812.1
466097.1
Chew bet
Garnet
438900
602235
unknown
Emerald
465080.2
482971.6
Das
Beryl
438724
602606
unknown
Emerald
358434.4
467267.6
Dilo
Garnet
438919
602625
unknown
Emerald
468603.1
506981.5
Web
Beryl
439486
602881
unknown
Jasper/ Chalcedony
469050.1
466450.8
Das
27
About the Ministry of Mines
In compliance with the market oriented economic policy of Ethiopia, the parliament
declared that it is the continuing policy of the Federal Government in the national interest
to foster and encourage private enterprises in developing economically sound and stable
mineral mining.
Accordingly, the Federal Government’s Ministry of Mines and Energy is responsible to
administer and supervise all large scale mining operations including issuing prospecting,
exploration and mining licenses for foreign investors and to these in joint venture with
Ethiopians as per the reform issued in 1998 on the Mining proclamation following the
realization of previous shortcomings of earlier laws and policies.
The reform clearly stipulated the responsibility of National Regional Governments to
issue licenses and administer all small scale mining operations owned by Ethiopians and
collecting all fees in addition to issue prospecting and exploration licenses for national
investors.
Mining Legislation
In June 1993 new Mining and Mining Income Tax Proclamations were issued having
considered knowledge-based experiences in some competitive countries and given the
following provisions;
• Invite private investment in all kinds of mineral operations;
• Provides a prospecting license for one year;
• Provides an exploration license for an initial period of three years and
renewed twice for one year each;
• Provides a mining license for 20 years and renewed for 10 years unlimitedly;
• Guarantee the licensee’s right to sell all the minerals locally or abroad giving
marketing freedom;
• Provides for exemptions from custom duties and taxes on equipment,
machinery, vehicles and spare parts;
• Gives securities of tenure;
• Gives clear provisions on fiscal and other issues;
• Considering taxation on repatriation of profits and capitals, a licensee shall
pay a 2-5% royalty on ad Val Orem at production site, and a 35% income tax
on taxable income. Taxable income is computed by subtracting from gross
income for any accounting year all allowable revenue expenditure, a four
years straight line depreciation, reinvestment deduction and permitted loses;
and
28
•
The mining proclamation guarantees the opening and operation of a foreign
currency account in banks in Ethiopia, retention of portion of foreign currency
earning and remittances of profits, dividends, principal and interest on a
foreign loan etc. out of Ethiopia.
Of course this fiscal package is still subject to frequent reviews for maintaining a balance
between the objective of the government and investors as is evident by a series of
amendments of the 1993.
INVESTMENT CLIMATE OF ETHIOPIA
The Federal Democratic Republic of Ethiopia has created a conducive investment
environment to ensure and promote private investment to play a leading role in the
development of the national economy.
This favorable climate for foreign investment has been created as consequence of the
solid foundation of political and economic reform, particularly the stably secured
macroeconomic reforms which are achieved by carefully managed sequential reforms
coupled with faire fiscal and monetary policies. By the virtues of Ethiopia’s unique and
untapped natural resources, its proximity to middle eastern and European markets, its 60
million population, and huge labor force both disciplined and easily trainable are some of
the comparative advantages worthy of consideration while investing in Ethiopia. This is
further enhanced by specific incentives and efficient administrative procedures.
Mineral Investment
Between 1974 and 1991 private investments were not allowed in the mineral sector. The
government was fully responsible for the exploration and development of the sector,
before the advent of the new economic policy of Ethiopia. In compliance with the new
market economic policy of Ethiopia the parliament declares that it is continuing to update
the policy of the Federal Government in the national interest to foster and encourage
private enterprises in developing economically sound and stable mineral mining.
For a successful implementation of the policy, a number of steps have been taken aiming
to boost the confidence of the private sector following the government’s strong believe
that rapid mineral development can only be realized when the private sector is given full
29
right of operating managing and owning mineral enterprises. This is the underlined
reason for the government’s active response to the concern of the International mining
Companies. Accordingly it has restricted its role to basic mineral resources exploration,
regulation and promotion only inorder;
•
to avoid the fear of controlling a large tract of prospective land by state owned
companies, and
•
to avoid the fear of seeable high risk due to unexpected unfair competition
with state owned enterprises.
In this connection a measure stick for such track record of the government’s commitment
is manifested by the privatized Lege Dembi Gold Mine, the only one government owned
large scale gold mining, and the Kenticha Tantalum Mine which is already in the pipeline
for privatization. This includes the reform of the mining law which is taking place since
1993 and many changes that have happened to justify the sincerity of the government.
Furthermore the commitment is much affirmed following the establishment of a fair and
clear cut mining legislation giving investors assurances of the fruits of their success. It
constitutes a fair setup of efficient and effective licensing and mineral right
administration system, a fair set of environmental laws, rules to monitor and mitigate and
reclamation effects by mining operation, fair laws to regulate the safety and health of the
work fore and securing of tenure. It also gives freedom to license holders with a number
of incentives including low royalty, exemption from custom duties and taxes on the
equipment, machineries vehicles, and spare parts necessary for mineral operations with a
10 years provision to allow investors to carry forward losses.
Geological Survey of Ethiopia (GSE)
P.O.Box 2302, Addis Abeba, Ethiopia
Tel: (251-1) 463325
Fax: (251-1) 463326, 712033
E-mail: [email protected]
Source of information: Geological Survey of Ethiopia (GSE), Ethiopian Mineral
Development Share Company (EMDSC).
Prepared by Sentayehu Zewdie; Wondafrash Mammo; Geremew Negassa
Address: [email protected]; [email protected]; [email protected]
30
Reference:
Astrup, J. 1955. Report on An alleged beryl occurrence in the region of Genale Dora
River Chembie). Unpublished report, Geological Survey of Ethiopia (GSE).
Dubois, C.G.B. 1976, Peridot in South Sidamo. Unpublished report, Geological
Survey of Ethiopia (GSE) Addis Ababa.
EMDSC, 2005, Gemstone occurrence in different parts of Ethiopia. Unpublished report,
Ethiopian Mineral development share Company, Addis Ababa, Ethiopia.
GDRBIRDMP, 2007. Genale-Dawa River Basin Integrated Resources Development
Master Plan. Part II, VolumeII.1, Mineral resources sector study. Ministry of
Water Resources, Addis Ababa
G/selassie, B, 2009. Report on Reconnaissance & Follow-up Exploration of Gemstone at
Baya Gundi area, Oromya National Regional State, Borena Zone.
Kazmine, V. 1972. Geology of Ethiopia Unpublished report EIGS Addis Ababa.
Ethiopia.
Kochemasov, GG, 1971. The geology and mineralization of the Chambi area, Sidamo.
Unpublished report. Geological Survey of Ethiopia (GSE) Addis Ababa.
Ministry of Information, 1998. Yearly Book, Ethiopia, Amharic version, Press and
Audiovisual Department, Addis Ababa. pp199.
Schumann, W. 2001. Gemstones of the World, Revised and expanded Edition. pp150.
Solomon, I. 1977. Olivine and garnet in Southern Sidamo. Unpublished report,
Geological Survey of Ethiopia (GSE) Addis Ababa.
Stone, M. 2002. Gems and Technology - Vision Underground.
( http://www.ganoksin.com/index.htm).
Tefera, M, Haro, W., Chernet, T. 1996. Explanation of the geological map of Ethiopia.
1:2,000,000 Scale. Geological survey of Ethiopia. Addis Ababa.
Tucci, P. 2005. Un an common gem from unusual source.
Tusguri, T. 2008. Assessment of gemstone in Dermidama area (Adola mineralized zone,
Southern Ethiopia, Msc Thesis, AAU.
31
4
32

Gemstone Potential Of Ethiopia - Geological Survey of Ethiopia

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